1. Field of the Invention
The invention relates to machines for injecting a material into a mold.
2. Description of the Prior Art
Such a machine is already known, designed for plastics and notably for elastomers, and includes an injection head having:
an axial cavity divided into a cylindrical injection chamber in which a piston is able to move and an injection channel connecting the injection chamber to an orifice for injecting into a mold, the injection channel being convergent at each end, that is on the one hand at its junction with the injection chamber and on the other hand just before the injection orifice, inside a removable nozzle;
a feed channel which opens out into the axial cavity and which is connected at the other end to a plasticizing cylinder which has heating means on the outside, while a worm rotates in its bore;
a non-return ball valve provided on the feed channel, which leaves the latter open when the piston moves In the injection chamber away from the injection orifice, so that the chamber is then fed with elastomer from the plasticizing cylinder, and which closes the feed channel under the effect of the injection pressure when the piston moves towards the injection orifice, so that the elastomer is then expelled through the injection orifice; and
a controlled obturator disposed on the injection channel, in order to close off the latter when the piston moves in the injection chamber away from the injection orifice, and to leave the injection channel open when the piston moves in the opposite direction.
The invention aims to provide an injection molding machine which is suitable in particular for a suspension of particles, such as metallic or ceramic particles, and for mixture thereof, of the type described in the documents WO-A-8807902 and WO-A-8807903, and more generally sludges or plastics loaded with materials liable to form deposits.
The inventors have in fact found that, even by eliminating the plasticizing means, conventional injection molding machines, including the one mentioned above, are not capable of functioning correctly with such suspensions of particles.